8.3 GNU Programs: how to avoid nana sometimes

Imagine you¹ are building a GNU program. Ideally it should run on systems without any other software including GCC, GDB and even Nana.

To achieve this noble goal you can provide your configure script with a ‘--without-nana’² flag which then ‘#define's’ ‘WITHOUT_NANA’. You should also use the ‘VL’ macro rather than ‘L’ macro since ‘L’ takes a variable number of arguments and will break non GNU C preprocessors.

     int half(int n) {
       /* Don't use L(...) since it takes a variable number of args! */
       VL(("hello world = %d\n", 10)); /* Note the doubled (( */
       ...;
     }